DNA
Adenine
Guanine
Thymine
Cytosine
"the blueprint of life"
So, what is DNA? Its a large molecule found in
every cell of your body. It's made of building
blocks called nucleotides (adenine, guanine,
thymine and cytosine). The order (or
sequence) of these nucleotides codes for the
different proteins that make up your body. In
humans this sequence is about 3 billion
nucleotides (or base pairs) long and every cell
contains the entire sequence (or genome).
DNA is bundled in structures called chromosomes found in the nucleus of every cell.
ATCCTTCT --TAGGAAGA --- complementary strand
Each nucleotide is composed of a
phosphate, pentose sugar and a nitrogenous base
DNA is composed of 2 strands that run in opposite directions (antiparallel) with nucleotides holding the strands together by hydrogen
bonds. Adenine (A) always pairs with Thymine (T) with 2 H-bonds and
Cytosine (C) always pairs with Guanine (G) with 3 H-bonds. Because
of this pairing you can always figure out the sequence of the opposite
(complementary) strand by knowing the sequence of only one strand.
These strands bend into a shape described as a double helix.
adenine,
thymine,
cytosine or
guanine
Each chromosome is divided into different regions called genes
which are each transcribed into RNA which is then translated
into different proteins. Sometimes people have a version
(allele) with a different sequence (a mutation) which can cause
a disease such as cystic fibrosis, Huntington disease or
muscular dystrophy.
All living organisms from bacteria, to cats, to humans, use
DNA to store all of their hereditary information.
You have 46 chromosomes of DNA in each
cell. 23 are from your father and 23 from your
mother. This gives you 2 copies of each gene.
DNA stands for deoxyribonucleic acid
Attribution-Noncommercial 3.0 United States, more free study guides at www.Biology101.org, copyright Anthony D'Onofrio